One way valve that uses fluid pressure to open and close the valve

ABSTRACT

A positive pressure one way medical valve contains an inlet ( 10 ), outlet ( 11 ), an internal flow path between the inlet and the outlet and a plunger ( 12 ) movable between a retraced sealing position, where backflow is reduced or prevented and an extended open position, where fluid can flow from the inlet to the outlet. The plunger is moved from the retraced to the extended position by insertion of a tip onto the inlet ( 10 ). A variable volume chamber ( 23 ) is defined partially by an elastomeric member ( 14 ) that is stretched, when plunger is in the extended position and reduced, when the plunger is in the retraced position so to increase or decrease the volume of the chamber respectively. A valve ( 50 ), which is movable between open and closed positions by the presence or absence of fluid passing through the inlet, immediately seals the flow pathway before the plunger is retraced.

FIELD OF THE INVENTION

This invention is directed to a valve that can be attached to acatheter, a needle or any other type of injecting device and that has aparticular configuration to prevent backflow. The invention isparticularly directed to a needle free access valve for use in a needlefree intravenous access system. The invention is also particularlydirected to a one-way valve to prevent backflow, and where the one-wayvalve contains a valve or similar device that opens, and importantlythat also closes by the presence or absence of fluid flow such that theone-way valve can close and therefore prevent or reduce backflow withoutneeding, at least initially, to move any part of the valve. Theinvention is also directed to a one-way valve having a plunger that doesnot directly contact the interior wall of the valve.

BACKGROUND ART

A needle free access valve is one where the valve can be opened using aneedleless syringe. A needleless syringe is a syringe where the needlehas been removed such that the front of the syringe has only the luertaper or luer lock. Such valves are known but suffer from a number ofdisadvantages.

A serious disadvantage with many existing one-way valves is that fluidcan flow back into the valve from the body cavity or the body in whichthe needle etc has penetrated. This results in contamination, and apotential health hazard. Most valves are provided with some form ofspring or bias to naturally bias the valve back into the closedposition.

In our earlier international patent application PCT/AU02/00861 there isdescribed a one way valve that delivers a positive pressure to preventbackflow. In this valve arrangement, there is provided a sliding plungerwhich is connected to a biasing web and movement of the plungerstretches and retracts the web. The web forms part of a variable volumechamber to keep a positive pressure.

One disadvantage with this valve and with most other one-way valves usedin the medical area is that the valve typically contains a slidingplunger that slides between the open position and the closed position.The sliding plunger is typically biased back to the closed position.Insertion of a luer tip or other type of device into the inlet of theone-way valve pushes the sliding plunger against the bias to the openposition. Therefore, the plunger cannot move to the closed positionuntil the luer tip or other device has been removed from the inlet.Thus, when the fluid flow through the device ceases, the plunger remainsin the open position (and therefore backflow is not prevented) untilsuch time as the luer tip or other device has been removed from theinlet. This can create circumstances where a small amount of backflowcan still occur, or where there is a time delay between the fluid flowceasing, and removal of the tip or other device from the inlet of theone-way valve (which then allows the plunger to move to the closedbackflow prevention position).

Therefore, there would be an advantage if it were possible to provide aone-way valve that may contain parts that move between an open positionand a closed position (for instance such as described in our earlier PCTapplication listed above) but which can also contain some form of valveor sealing member that is operable between a open fluid flow positionand a closed position by the action of fluid. An advantage of this isthat as soon as the fluid flow stops, the valve can move to the closedposition before any further parts of the valve move (e.g. the plunger).The valve can be in addition to the ordinarily moving parts of theone-way valve, or can replace at least some of the ordinarily movingparts of the one-way valve.

Another disadvantage with backflow prevention valves is that there isstill the possibility of blood finding its way ultimately close to theinlet of the valve which can be a source of hazard. Therefore, therewould be an advantage if it were possible to provide a one-way valvethat could reduce or eliminate this occurrence.

OBJECT OF THE INVENTION

It is an object of the invention to provide a valve assembly for use inthe medical field and which can reduce or entirely prevent theoccurrence of backflow from the body cavity etc back through the valveassembly, and especially without requiring parts of the valve to slidebetween an open position and a closed position.

It is further object of the invention to provide a valve assembly thatmay at least partially overcome the abovementioned disadvantages orprovide the public with a useful or commercial choice.

In one form, the invention resides in a one way valve assembly thatcomprises:

1. an inlet and an outlet,

2. a flow pathway that extends through the valve assembly from the inletto the outlet,

3. a plunger that is positioned in the flow pathway and which can movebetween a forward open position where fluid can flow from the inlet tothe outlet, and a retracted closed position where fluid flow is reducedor prevented from flowing from the inlet to the outlet,4. an at least partially elastic web that has an outer end fixed to thevalve assembly, and an inner portion which engages with the plunger suchthat reciprocation of the plunger from the retracted position to theforward position causes at least part of the web to stretch,5. a variable volume chamber having walls at least partially defined bythe plunger and the web, the chamber forming part of the flow pathway,the chamber having smaller or nil volume when the plunger is in theretracted position, and a larger volume when the plunger is in theextended position, whereby upon retraction of the plunger, the variablevolume chamber reduces in volume which results in a pumping action topump fluid through the fluid pathway towards the outlet, therebyreducing or preventing backflow, and6. a valve positioned within the flow path and which is movable betweenan open position enabling fluid to flow towards the outlet of the valve,and a closed position preventing backflow of fluid through the inlet,characterised in that the valve is moved to the open position by theflow of fluid, and the valve is moved to the closed position by theabsence of flow of fluid.

In one form, the valve may be naturally biased to the closed positionand is moved to the open position by the flow of fluid and will move tothe naturally closed position when the flow of fluid stops.

The one-way valve assembly will typically contain the valve as describedabove and may also contain a sliding plunger which may be similar tothat described in our earlier PCT application. The sliding plunger isoperated by insertion or removal of a tip through the inlet of the valveassembly, and the valve is operated by fluid flow.

An advantage of this arrangement is that backflow can be prevented assoon as fluid flow through the valve assembly ceases irrespective ofwhether the tip has been removed from or is still in the inlet of thevalve assembly.

Although there is a preference to provide a one-way valve assemblycontaining a sliding plunger as described above, in a broad form of theinvention, there may be provided a one-way valve assembly that comprisesan inlet and an outlet, a variable volume chamber which increases involume as fluid flows through the assembly from the inlet to the outlet,and which decreases in volume upon removal of a tip or similar devicefrom the inlet, or upon slowing or stopping of fluid flow from the inletto the outlet, the decrease in volume providing a positive pressure toreduce or to prevent backflow, and a valve which is movable between anopen position where fluid can flow from the inlet to the outlet, and aclosed position where backflow is reduced or prevented, the valve beingmovable from the closed position to the open position by fluid pressure,and being movable from the open position to the closed position upon areduction or stopping of the fluid pressure.

With this arrangement, the valve apparatus can be attached to a syringe(or other device), and a needle, catheter or other body-injecting devicecan be attached to the apparatus. The contents of the syringe can thenbe passed through the apparatus and into the body by depressing theplunger into the forward (open) position. As the plunger moves towardsthe forward position, it stretches at least part of the web and thevariable volume chamber adopts the larger volume. However once thesyringe is removed, or retracted, the web retracts to its initialposition, causing the plunger to be pushed back into the closed positionand at the same time contracting the variable volume chamber. Thecontraction causes a positive pressure inside the apparatus that meansthat backflow does not occur. Indeed, it is found that the positivepressure is sufficient to at least partially “pump” any residual fluidin the apparatus through the outlet upon retraction of the plunger. Thisis in contrast to known devices where retraction of the plunger orclosure of the valve often allows backflow of fluid through the outletand into the valve apparatus.

In addition, the valve assembly contains the valve that is operated bythe fluid flow and not by any insertion or removal of a luer tip etcinto the valve assembly. Thus, as soon as the fluid in the syringe stopsflowing through the valve assembly, this particular valve will move tothe closed position even when the plunger is still in the open position.

The valve assembly may have features similar to or identical with thosedescribed in our above referenced PCT application, and therefore mayhave an outer body formed in two parts that are attached together. Thetwo parts may comprise a top part, and a base part. The top part issubstantially hollow and suitably contains an outer passageway ofsmaller diameter or cross-section, and an inner passageway of largerdiameter or cross-section, the inner passageway forming part of aninternal chamber.

The base part may be substantially hollow and may contain an outerpassageway of smaller diameter or cross-section, and an inner passagewayof larger cross-section or diameter and which forms part of the internalchamber that is also defined by the top part. Thus, when the two partsare attached, there is provided a substantially central internalchamber. The outer passageway of the base part may be surrounded byattachments to allow the outlet to attach to a needle etc.

The apparatus has a flow pathway that extends through the valve assemblyfrom the inlet to the outlet, and typically through the central internalchamber described above.

The apparatus may contain a plunger. The plunger, if present, ismoveable between a forward open position where the plunger moves moretowards the outlet, and a retracted closed position where the plunger ismore towards the inlet. The plunger typically slides or reciprocatesbetween the two positions.

The plunger has a forward portion which is typically a projecting noseportion. Suitably, the plunger also has a rear body portion. The noseportion and the body portion may be formed integrally. The plungersuitably has a fluid flow pathway extending at least partiallytherethrough. The fluid flow pathway may comprise an internal flowpassageway extending through the nose portion which means that the noseportion may have an opening. Suitably, the internal flow passagewayincludes a transverse through bore in the plunger such that fluid canpass through the through bore and through the flow passageway thatextends through the nose portion.

The rear body portion of the plunger is typically configured anddimensioned to substantially fill the outer passageway in the top partof the valve assembly. The rear body portion typically has a sealingface extending about the rear body adjacent the end face and which sealswith the internal wall of the outer passageway.

The plunger may have an engagement means to engage with the elastic web.The engagement means may comprise an annular step or shoulder portion onthe plunger and which can catch against or engage with the elastic webupon forward movement of the plunger. Alternatively, the plunger canpush against the web.

The apparatus has an at least partially elastic biasing web/diaphragm or“sock”. The web may be formed of a rubbery elastic material having agood memory. In one form of the invention, the web may be formed as aseparate component. The elastic web may be substantially circular withan opening through which part of the plunger can project. The web mayhave a peripheral edge that is held against movement in the valveassembly. Suitably, the peripheral edge also comprises a sealing edge.Preferably, the web is elastic and can therefore be stretched uponforward movement of the plunger.

The web may have an internal opening, which is typically a centralopening and through which part of the plunger can pass, which istypically a nose portion of the plunger. If desired, the plunger may beprovided with an annular recess to capture the wall of the internalopening. With this arrangement, the plunger may be provided with seals.

It is envisaged that the plunger and the web can be formed integrally.

The valve that forms part of the valve assembly and which is operated byfluid flow may have various configurations and may be attached invarious places in the valve assembly, but will typically be positionedto intercept the fluid flow. It is envisaged that the valve will bepositioned in the inlet area of the valve assembly, and will usually bepositioned between the inlet and the variable volume chamber.

In one form of the invention, the valve may be attached relative to theplunger such that the valve moves as the plunger moves.

However, in another form of the invention, the valve may be attached topart of the assembly other than the plunger such that the valve does notslide or move with the plunger. In this form of the invention, the valvemay be formed separately and fitted to the remainder of the valveassembly, or may be formed integrally with a part of the valve assembly.

It is preferred that the valve comprises at least one member that canmove, typically by flexing or expanding or bending between the openposition and the closed position. For this reason, it is preferred thatthe valve contains a resilient portion or consists essentially of aresilient member.

It is preferred that the valve is positioned in the fluid flow pathwaysuch that when the valve is not subjected to the force of fluid flow,the valve adopts the closed position where its seals the fluid flowpathway. However, when subjected to the force of fluid flow, the valvecan move to the open position.

It is preferred that the valve is manufactured from material, orotherwise made such that it naturally adopts the closed position, suchthat when the fluid flow stops, the valve will move naturally to theclosed position without requiring any further actuating force on thevalve. In one form, the valve can be made from a plastic material or arubber material, or an elastomeric material which will return to a rest(sealing) position when the fluid flow force stops. The material maycomprise a silicone material, a polyethylene, a polyvinyl chloride,nylon, other types of homopolymers and copolymers, and the like. Thematerial may also comprise a metal such as thin spring steel. It is alsoenvisaged that the valve can be made of composite materials, laminatedmaterials and the like.

The assembly will typically contain at least one valve of this design,but it is envisaged that there may be circumstances where two or more ofsuch valves would be desirable. For instance, under instances of highback pressure, there may be an advantage in providing more than onevalve.

The valve may have various different designs. The valve may be disk likeor planar and may be circular when viewed in plan (typically if thefluid pathway in this area is circular). However, the valve may haveother shapes such as oval, rectangular, triangular, tubular, and thelike. The valve may have a diameter or cross-section which will dependon the size of the fluid flow pathway, but for a one-way valve oftypical size, it is envisaged that the valve will have a diameter orcross-section size of between 3-25 mm. The thickness of the valve willalso depend on the material and it is envisaged that the valve will havea thickness of between 0.5-5 millimeters and typically between 0.5-3millimeters. Of course, no particular limitation should be placed on theinvention merely by the provision of these dimensions which have beengiven for illustrative purposes only.

The valve may be attached to or relative to the plunger, and willtypically be attached to or relative to the part of the plunger that isadjacent the inlet of the valve assembly.

This part of the plunger can be called the “base part”. In one form, thevalve may comprise a disk like member attached to the front of the basepart of the plunger. The disk like member may be spaced slightly forwardof the plunger by at least one spacing member and against a central partof the valve. The valve is preferably made from resilient material andthe peripheral part of the valve is not supported and can thereforeflex. The valve can be positioned adjacent an internal wall of the fluidflow pathway such that the valve will naturally adopt a sealing positionto seal the fluid flow pathway, but the peripheral part of the valve canflex away from the sealing position (and therefore to the open position)upon the force of fluid passing through the inlet. In this form of theinvention, it is preferred that the valve is positioned such that when aluer tip of a syringe is inserted into the inlet of the valve assembly,it will press against the valve. This can further assist in the sealingprocess and will be described in greater detail below.

In another form the valve may be attached to the end of the plunger, andtypically to the end that is adjacent the inlet of the valve assembly.In this form, the plunger may contain a flow passageway, and the valveextends over the flow passageway. The valve may be formed fromelastomeric or resilient material and will typically contain a smallopening extending through the valve body. When the valve is in the“rest” or natural position, the small opening is squeezed closed, orotherwise closed. However, when fluid pressure is applied to the valve,the valve will flex and this will cause the small opening to openthereby allowing fluid to pass through the valve assembly. However, assoon as the fluid flow stops, the valve will move back to the rest ornatural position which will squeeze the opening to the closed position.

In another form, the valve is not attached to the plunger, but isinstead attached to a different part of the valve assembly. In thisparticular form of the invention, the valve may comprise a tubularsleeve which can stretch under the force of fluid. The tubular sleevecan be positioned inside the fluid flow passageway and in such aposition that the sleeve is in a natural sealing position where itsseals against the plunger, but the force of fluid will cause the tubularsleeve to expand or move to enable fluid to pass through the valveassembly.

In a modification of the form of the invention described immediatelyabove, the sleeve may be tubular but instead of being entirelystretchable, the sleeve may comprise a “split sleeve” that can open upto enable fluid to flow through the valve assembly but which willnaturally adopt a closed position where the split in the sleeve isclosed. In a modification to this form of the invention, the sleeve maycomprise a portion that is rigid and a portion that is stretchable toenable the sleeve to move between the open position and the closedposition.

In another form of the invention, and in which an embodiment isdescribed as the “sixth” embodiment, and illustrated in FIGS. 22-24,there is provided a positive pressure one way valve assembly thatcomprises:

1. An inlet and an outlet,

2. A flow pathway that extends through the valve assembly from the inletto the outlet,

3. A plunger that is positioned in the flow pathway and which can movebetween a forward open position where fluid can flow from the inlet tothe outlet, and a retracted closed position where fluid is preventedfrom flowing from the inlet to the outlet, the plunger having a forwardportion,4. An at least partially elastic web that has an outer end fixed to thevalve assembly, and an inner portion which engages with the plunger suchthat reciprocation of the plunger from the retracted position to theforward position causes at least part of the web to stretch,5. A variable volume chamber having walls defined by the plunger and theweb, the chamber forming part of the flow pathway, the chamber havingsmaller or nil volume when the plunger is in the retracted position, anda larger volume when the plunger is in the extended position, wherebyupon retraction of the plunger, the variable volume chamber reduces involume which results in a pumping action to pump fluid through the fluidpathway towards the outlet, thereby reducing or preventing backflow, and6. An annular seal on the piston and which seals against an internalwall of the valve when the piston is in the retracted position to sealoff the variable volume chamber such that the variable volume chamberdoes not form part of the flow pathway.

With this arrangement, the apparatus can be attached to a syringe (orother device), and a needle, catheter or other body-injecting device canbe attached to the apparatus. The contents of the syringe can then bepassed through the apparatus and into the body by depressing the plungerinto the forward (open) position. As the plunger moves towards theforward position, it stretches at least part of the web and the variablevolume chamber adopts the larger volume. However once the syringe isremoved, or retracted, the web retracts to its initial position, causingthe plunger to be pushed back into the closed position and at the sametime contracting the variable volume chamber. The contraction causes apositive pressure inside the apparatus that means that backflow does notoccur. Indeed, it is found that the positive pressure is sufficient toat least partially “pump” any residual fluid in the apparatus throughthe outlet upon retraction of the plunger. This is in contrast to knowndevices where retraction of the plunger or closure of the valve oftenallows backflow of fluid through the outlet and into the valveapparatus.

The valve assembly may have an outer body formed in two parts that areattached together. The two parts may comprise a top part, and a basepart. The top part is substantially hollow and suitably contains anouter passageway of smaller diameter or cross-section, and an innerpassageway of larger diameter or cross-section, the inner passagewayforming part of an internal chamber. The outer passageway may containlongitudinal slots or recesses that comprise fluid ports the reason forwhich will be described in greater detail below.

The base part may be substantially hollow and may contain an outerpassageway of smaller diameter or cross-section, and an inner passagewayof larger cross-section or diameter and which forms part of the internalchamber that is also defined by the top part. Thus, when the two partsare attached, there is provided a substantially central internalchamber. The outer passageway of the base part may be surrounded byattachments to allow the outlet to attach to a needle etc.

The apparatus has a flow pathway that extends through the valve assemblyfrom the inlet to the outlet, and typically through the central internalchamber described above.

The apparatus has a plunger. The plunger is moveable between a forwardopen position where the plunger moves more towards the outlet, and aretracted closed position where the plunger is more towards the inlet.The plunger typically slides or reciprocates between the two positions.

The plunger has a forward portion which is typically a projecting noseportion. Suitably, the plunger also has a rear body portion. The noseportion and the body portion may be formed integrally. The plungersuitably has a fluid flow pathway extending at least partiallytherethrough. The fluid flow pathway may comprise an internal flowpassageway extending through the nose portion which means that the noseportion may have an open outer end. Suitably, the internal flowpassageway includes a transverse through bore in the rear body portionsuch that fluid can pass through the through bore and through the flowpassageway that extends through the nose portion.

The rear body portion of the plunger is typically configured anddimensioned to substantially fill the outer passageway in the top partof the valve assembly. Suitably, the rear body portion has an end facethat is substantially flush with the end of the top part of the valveassembly that can make cleaning of this area quite easy. The rear bodyportion typically has a sealing face extending about the rear bodyadjacent the end face and which seals with the internal wall of theouter passageway.

The plunger may have an engagement means to engage with the elastic web.The engagement means may comprise an annular step or shoulder portion onthe plunger and which can catch against or engage with the elastic webupon forward movement of the plunger. Alternatively, the plunger canpush against the web.

The apparatus has an at least partially elastic biasing web or “sock”.The web may be formed of a rubbery elastic material having a goodmemory. In one form of the invention, the web may be formed as aseparate component. The elastic web may be substantially circular withan opening through which part of the piston can project.

The web may have a peripheral edge that is held against movement in thevalve assembly. Suitably, the peripheral edge also comprises a sealingedge. Preferably, the web is elastic and can therefore be stretched uponforward movement of the plunger.

The web may have an internal opening, which is typically a centralopening and through which part of the plunger can pass, which istypically a nose portion of the plunger. If desired, the plunger may beprovided with an annular recess to capture the wall of the internalopening. With this arrangement, the plunger may be provided with seals.

It is envisaged that the plunger and the web can be formed integrally.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described with reference to thefollowing drawings in which:

FIG. 1. Illustrates a typical design of a one-way valve assemblyaccording to an embodiment of the invention.

FIGS. 2-4. Illustrate a first embodiment of the invention whichcomprises a valve assembly that contains a valve attached to the end ofthe plunger and which can flex between an open position and a closedposition.

FIGS. 5-7. Illustrate a second embodiment of the invention whichcomprises a valve which is also positioned over the end of the plungerbut which contains an opening extending through the valve and which canopen or close.

FIGS. 8-10. Illustrate a third embodiment of the invention whichcomprises a valve of tubular design that is not attached to the plungerbut is instead attached to the internal wall of the valve assembly.

FIGS. 11-13. Illustrate a fourth embodiment of the invention whichcomprises a valve of tubular design, but where the valve is not aseparate item but has instead been co-moulded with part of the valvehousing.

FIGS. 14-21. Illustrate a fifth embodiment of the invention whichincludes a flexible collar.

FIGS. 22-24. Illustrate a sixth embodiment of the invention.

BEST MODE

Referring to the drawings, and initially to FIG. 2, there is illustrateda valve assembly which comprises an inlet 10 and an outlet 11, a flowpathway that extends through the valve assembly from inlet 10 to outlet11, a plunger 12 that is positioned in the flow pathway and which canreciprocate between a pushed forward open position illustrated in FIGS.3 and 4, and a retracted closed position illustrated in FIG. 2, anelastic web 14 which extends about plunger 12, and a variable volumechamber 16 (see FIG. 3) which is larger in FIGS. 3 and 4 and smaller ornil in FIG. 2.

Referring to the parts in greater detail, the valve assembly in theembodiment comprises an outer body that is formed of two parts that areattached together, the two parts being a first (top) part 17 and asecond (base) part 18. These parts are formed of plastic material andare joined together by any suitable method. Part 17 is substantiallyhollow. Part 17 comprises an outer passageway 19 which is circular andwhich has a smaller diameter, and an inner passageway 20 which is alsocircular and which has a substantially larger diameter. Similarly, part18 has an inner passageway 21 that has a substantially larger diameterthan outer passageway 22. When the two parts are joined, the two largerdiameter passageways together form an internal chamber 23. Outerpassageway 22 terminates in outlet 11, while outer passageway 19terminates in inlet 10.

Part 18 contains a standard luer lock fitting 26 which extends aboutpassageway 22 and which functions to allow a needle etc to be attachedto this part of the assembly. Of course, other types of attachments canalso be used.

Inner passageway 21 has a diameter that is smaller than inner passageway20. Thus, the wall of inner passageway 21 passes into inner passageway20 this being best illustrated in FIG. 2. Moreover, the wall has alength that results in the wall being spaced somewhat from wall of toppart 17 (see FIG. 2). This spacing facilitates the attachment of theelastic web that will be described in greater detail below.

Plunger 12 is formed of plastic material and comprises a unitary body.The plunger has a particular configuration that provides a nose portion13, and a rear body portion 29 (best illustrated in FIG. 3). Noseportion 13 is slightly tapered and has a through passageway 30 whichpasses through an open outer end 31 and functions to allow fluid to flowthrough the valve assembly. Body portion 29 is provided with atransverse through bore 32 through which fluid can pass. Body portion 29has a substantially cylindrical outer wall.

When plunger 12 is pushed forwardly from the position illustrated inFIG. 2 to the position illustrated in FIG. 3, the plunger only moves bya few millimeters, but this movement is sufficient to allow fluid topass along the outside wall of body portion 29, through bore 32 throughpassageway 30 and through outlet 11. Conversely, when the plunger isretracted from the position illustrated in FIG. 3 to the positionillustrated in FIG. 2 the plunger again seals against passage of fluidfrom inlet 10 through outlet 11.

The plunger is biased back to its retracted position by the elastic web14 which also provide additional functions. Elastic web 14 is made of arubbery elastic material having an excellent memory. The elastic web issubstantially circular and has a base peripheral edge 41 that isthickened with respect to the thickness of the portion immediately nextto the peripheral edge. The thickened peripheral edge 41 is trappedbetween the wall of part 18 and the inner wall of part 17. Peripheraledge 41 also functions to seal the fluid pathway in the apparatus.

As the plunger 12 is pushed to the forward open position, it willstretch the biasing web 14 which forms part of the variable volumechamber 16 and the movement will increase the volume of chamber 16. Whenthe plunger is retracted to the closed position (and web 14 forms partof a biasing means to bias the plunger back to the closed position), thevariable volume chamber will reduce in volume and will provide apositive pressure in the valve to prevent backflow of any fluid intooutlet 11.

The web is designed such that when the plunger 12 is in the retractedclosed position, there is still some tension in the web to keep theplunger in the retracted position.

A small air passageway 56 is provided to allow air to pass into chamber23 upon shrinking of the web and to allow air to pass out of chamber 23upon stretching of the web.

The valve assembly prevents back flow of fluids by maintaining apositive pressure in chamber 16.

Another advantage with the arrangement is that possibly contaminated airis kept separate from the fluid flow pathway of the valve assembly byvirtue of the web 14 and the various seals.

The arrangement described above is similar to that described in ourearlier international patent application, and has been repeated merelyto describe the main part of the valve assembly.

However, one disadvantage with the arrangement described above is thatthe valve assembly can only seal once the plunger 12 has been retracted.As the plunger 12 cannot be retracted unless the tip 15 (see FIG. 3) hasbeen pulled out of inlet 10, the valve assembly suffers from adisadvantage that if the fluid flow through tip 15 stops, the valveassembly remains in the “open” position as the plunger 12 is still inthe pushed forward open position by virtue of tip 15.

The present invention is directed to a modification of the above valveassembly that enables the valve assembly to prevent backflow even whenthe plunger is in the pushed forward open position.

FIGS. 2-4 illustrate the first embodiment that enables this to happen.FIGS. 5-7 illustrate a second embodiment. FIGS. 8-10 illustrate a thirdembodiment that enables this to happen, and FIGS. 11-15 illustrate afourth embodiment. Of course, the invention should not be limited to theprecise description of the embodiments, and should be extend to thegeneral concept of providing a valve assembly that can prevent backpressure as soon as the fluid flow stops.

Referring initially to FIG. 1, this is a general view of the outside ofthe valve assembly and shows the inlet 10 and the outlet 11.

Referring to FIGS. 2-4, the general parts of the valve assembly havebeen described above. However, a modification is in the provision of anend valve 50 which is fitted to the end of plunger 12 that is positionedadjacent inlet 10. That is, valve 50 is the “first point of contact”with a tip 15. In this particular embodiment, the valve 50 comprises asubstantially circular flat disk which is made of resilient or bendablematerial. The valve is supported by a pair of spacing members 51 thatare attached to plunger 12 and that space the valve a few millimeters infront of plunger 12. The spacing members hold the central part of thevalve relatively rigid, but it can be seen that the spacing members arespaced inwardly from the peripheral edge of the valve. This means thatthe peripheral edge of the valve is not supported by the spacing members51 and can flex inwardly. The flexing function causes the valve to moveto the open position enabling fluid to flow through tip 15 and throughthe remainder of the valve assembly in a manner described above. Thus,referring to FIG. 2, the valve 50 is in the closed position where thevalve is planar. A tip 15 (see FIG. 3) can be inserted through inlet 10and pushed into the valve assembly. As this happens, plunger 12 will bemoved forwardly to enlarge the variable volume chamber 16. Also, the tippushes against valve 10. At this stage though and until fluid flowsthrough tip 15, valve 50 remains in the closed position illustrated inFIG. 4. That is, valve 50 does not flex and remains in a substantiallyplanar configuration.

As soon as fluid flows through tip 15, the fluid force will cause theperipheral edge of valve 50 to flex inwardly (see FIG. 3) which nowmoves the valve to the open position and enables fluid to flow throughthe variable volume chamber 16, through the transverse bore 32, andultimately through outlet 11.

However, as soon as the fluid flow stops, the valve 50 will immediatelyreturn or flex back to the flat or planar configuration (see FIG. 4)which will immediately prevent fluid from flowing in the reversedirection. It can be seen though that the plunger 12 is still in theforward “open” position. Also, in this position, valve 50 seals againstthe front of tip 15.

As the tip 15 is pulled out of inlet 10, the plunger 12 will move backto the retracted position which will reduce the size of the variablevolume chamber 16 to create a positive pressure to pump out anyremaining fluid through outlet 11, and to therefore prevent anybackflow. However, during this process, valve 50 is closed, which meansthat it seals against back pressure as well.

Thus, the provision of valve 50 will cause immediate sealing of thevalve assembly even when the plunger 12 is in the forward open position,as soon as fluid flow stops. There is now no longer a requirement tohave the additional retraction steps of plunger 12 to create the seal.Although it is preferred that the plunger also provides a seal, it isenvisaged that the plunger can also function merely to expand andretract the variable volume chamber 16, and that the primary sealing isnow carried out by valve 50.

The remaining embodiments show further variations to this principle ofproviding a seal immediately upon stopping of fluid flow.

Referring to FIGS. 5-7, there is illustrated a valve 55. In thisembodiment, the plunger 12 is of a different design and is substantiallyhollow to enable fluid to flow through the plunger. However, fluid flowis prevented by valve 55 that functions as an end cap and which isattached over the otherwise open end of the plunger. The valve 55 isagain flexible but is naturally biased to the position illustrated inFIG. 5. Valve 55 contains a small central opening 56 which isillustrated best in FIG. 6. The central opening 56 opens only when thevalve 55 is bowed inwardly. Valve 55 moves from the naturally closedposition illustrated in FIGS. 5 and 7, to the open position whereopening 56 is open and which is illustrated in FIG. 5, by the force offluid passing through tip 15. Thus, as tip 15 passes through inlet 10(see FIG. 6) it will push against plunger 12 and move plunger 12 to theforward position which expands the variable volume chamber 16. At thisstage however it is important to note that valve 55 is still in theclosed position illustrated in FIG. 7 and in FIG. 5. The valve will notmove to the open position until fluid passes through tip 15 as the fluidpressure will cause valve 55 to bow inwardly (see FIG. 6) to open upopening 56. As soon as fluid stops flowing through tip 15, valve 55 willimmediately return to the rest position (FIG. 7) which will close theopening 56. Again, the plunger 12 is still in the forward position.

The tip 15 can then be withdrawn from inlet 10 and this will cause theplunger to be pulled back to the retracted position by the elastic web14, and in the process reducing the size of the variable volume chamber,creating a positive back pressure flow, thereby preventing backpressure. During this process, the valve 55 remains in the closedposition.

FIGS. 8-10 illustrates another variation to this general principle. Inthis variation, a tubular valve 60 is provided. The tubular valve 60 isnot attached to the plunger 12 (as is the case with the previousembodiments), but is instead attached to the inside wall of the flowpassageway and adjacent the inlet 10. The tubular valve 60 is made ofelastic material which means that it can be stretched to a largeopening, but the natural position of the tubular valve is a shrunkposition. The valve 60 has a diameter which enables the plunger 12 toslide through the valve between the plunger retracted positionillustrated in FIG. 8, and the plunger extended position illustrated inFIGS. 9-10. The plunger 12 in this particular embodiment contains aperipheral seal 61 that closes the flow passageway. Thus, when theplunger is in the retracted position illustrated in FIG. 8, the valveassembly is closed. A tip 15 can be inserted through the inlet (see FIG.9) and this causes the plunger 12 to be pushed forwardly until theperipheral seal 61 is no longer in sealing engagement with the insidewall adjacent the inlet 10. Instead, the peripheral seal 61 has moved toan enlarged portion 62 where there is no longer a sealing engagement.However, in this position, the tubular valve 60 seals against theperipheral seal 61 and therefore the flow passageway is still closed,because of the engagement of tubular valve 60 against seal 61. Thisparticular position is illustrated in FIG. 10.

As soon as fluid flows through tip 15, the force of the fluid issufficient to stretch the end of valve 60. This, in turn, releases thesealing engagement with valve 60 against seal 61 which means that fluidcan now flow through the valve assembly. This is illustrated in FIG. 9.Thus, as long as fluid flows through tip 15, the valve 60 is forced intothe stretched and open position. As soon as fluid stops flowing, valve60 snaps to the shut position which is illustrated in FIG. 10, eventhough the plunger 12 is still in the pushed forward position. Theplunger 12 will move back to the retracted position but only when tip 15is removed from the valve assembly, and this will also cause thevariable volume chamber 16 to shrink in volume and therefore create apositive pressure to prevent backflow.

FIGS. 11-13 illustrate another embodiment of the invention which issimilar to that described with reference to FIGS. 8-10 in that the valveis not attached to the plunger. In this particular embodiment, there isprovided a valve 70 which is not formed separately (as is the case inFIGS. 8-10) but which is part of the first part 17 and is extruded as aunitary structure. The valve 70 again engages with the peripheral seal61 of plunger 12 to prevent fluid flow, and the valve can again move tothe open position illustrated in FIG. 12 upon flow of fluid through tip15. As valve 70 is formed integrally with first part 17, the valve maynot be formed of stretchable material. Thus, in this embodiment, thevalve may be a “reed” type of valve where the tubular body contains asection separated from the remainder of the tubular body like a line.When the valve is in the closed position, the cut lines are sealed.However, when fluid flows through tip 15, the tubular body expands andthe cut lines enlarge. Again, as soon as fluid stops flowing, the valvemoves to the closed position without any movement of the plunger.

Referring to FIGS. 14-21, this illustrates a fifth embodiment of theinvention. In this embodiment, the valve assembly is slightly modifiedto reduce or eliminate bio fluids (e.g. blood) flowing over the inlet ofthe valve assembly. The valve assembly is similar to that describedabove in that it comprises two parts 80, 81 that are connected together.Part 80 contains the inlet 82 and part 81 contains the outlet 83. Aplunger 84 moves through the valve in a manner similar to that describedpreviously, and the valve assembly contains a variable volume chamberdefined, in part, by the resilient web 85. Plunger 84 contains a forwardportion 86 containing an end face 87. In this portion is provided anannular seat 88 that extends around this part of the plunger.

One slight disadvantage with this type of valve assembly is that uponretraction of the plunger from the forward (open) position to theretracted (closed) position, some blood can pass over end face 87 whichcan be a source of contamination. The fifth embodiment of the inventionprovides a means to reduce or eliminate this.

In this embodiment, the valve assembly contains one an additional partthat is illustrated in FIG. 15 and which comprises a plastic (typicallypolypropylene) base 90 containing an elastomer collar 91 overmouldedonto base 90. Collar 91 contains a plurality of slits 92 to facilitateflow of fluid and this will be described in greater detail below.Referring to FIG. 14, there is illustrated in section view the base 90and the collar 91. Collar 91 contains an internal opening (illustratedin FIG. 15) through which part of the plunger 84 can pass. This isillustrated in FIGS. 14, 16, 18, 19 and 21.

In use, the valve assembly is initially in the position illustrated inFIG. 14 where plunger 84 is in the fully retracted position such thatthe end face 87 is substantially flush with inlet 82.

When a medical device (e.g. a tip 93) is pushed into inlet 82 (thisbeing illustrated in FIG. 16), this will cause the plunger 84 to bepushed forwardly and will cause the resilient web 85 to stretch and willenlarge the variable volume chamber, this having been describedpreviously. Base 90 is fixed to housing part 80 of the valve assemblyand therefore does not move upon movement of the plunger 84. Similarly,collar 91 is attached to base 90 and does not slide with the plunger.

When the medical tip 93 has been pushed into inlet 82 as illustrated inFIG. 16, the annular seal 88 extending about plunger 84 has now moved toan enlarged portion when fluid can now flow through tip 93 and past seal88.

When fluid is caused to flow through the medical tip 93, the force ofthe fluid will push the resilient flaps 94 (see FIG. 15) of collar 91into an open position therefore allowing fluid to flow through the valveassembly. FIG. 17 illustrates this particular position where flaps 94have been pushed under the force of the fluid flow to no longer engagewith plunger 84. Instead, a fluid flow pathway is formed.

As soon as the fluid flow is stopped, the flaps 94 spring back to thesealing position where they seal against plunger 84 such that backflowis reduced or is eliminated. This position is illustrated in FIG. 19.However there is still the possibility of some blood flowing into theend face area 87 of the plunger such that when the plunger moves back tothe retracted position illustrated in FIG. 14, there will be bloodaround the inlet 82 of the valve assembly.

This can be reduced or eliminated by the embodiment illustrated in FIGS.16-21. Referring particularly to FIG. 20, this is the positionimmediately after fluid flow has stopped and the tip 93 is beginning tobe withdrawn. At this stage, the flaps 94 are sealed against the plunger84. The annular seal 88 on the plunger body has not yet moved intosealing engagement with the passageway in the housing and thereforefluid can still flow from the end face area 87 and into a temporarychamber 96 (see FIG. 20). Upon retraction of the tip (by a fewmillimeters), the plunger body 84 will begin movement back to theretracted position (also by a few millimeters), and this will cause thesize of volume of the temporary chamber 96 to increase. In turn, thiscauses the pressure in the temporary chamber to drop and this pressuredrop will cause any blood still in the end face area 87 to be “sucked”into the temporary chamber.

Further retraction of tip 93 (typically by a few more millimeters) willnow cause the plunger to be retracted sufficiently such that the annularseal 88 is now sealingly engaged with the internal passageway of thispart of the valve assembly, this position being illustrated in FIG. 21.In this position, the temporary chamber 96 is now sealed (by annularseal 88) which means that blood can not flow back to the end face area87 upon further retraction of the tip 93 and therefore furtherretraction of plunger 84.

Referring to FIGS. 22-24 and initially to FIG. 22, there is illustrateda valve assembly which comprises an inlet 210 and an outlet 211, a flowpathway that extends through the valve assembly from inlet 210 to outlet211, a plunger 212 that is positioned in the flow pathway and which canreciprocate between a forward open position illustrated in FIG. 22, anda retracted closed position illustrated in FIG. 23, the plunger havingan elongate forward nose portion 213, an elastic web 214 which extendsabout plunger 212, and a variable volume chamber 216 which is larger inFIG. 22 and smaller or nil in FIG. 23.

Referring to the parts in greater detail, the valve assembly in theembodiment comprises an outer body that is formed of two parts that areattached together, the two parts being a first part 217 and a secondpart 218. These parts are formed of plastic material and are joinedtogether by any suitable method. Part 217 is substantially hollow. Part217 comprises an outer passageway 219 which is circular and which has asmaller diameter, and an inner passageway 220 which is also circular andwhich has a substantially larger diameter. Similarly, part 218 has aninner passageway 221 that has a substantially larger diameter than outerpassageway 222. When the two parts are joined, the two larger diameterpassageways together form an internal chamber 223. Outer passageway 222terminates in outlet 211, while outer passageway 219 terminates in inlet210.

The outer passageway 219 in part 217 contains six radial open endedfluid transfer ports 224. Ports 224 comprise recesses in the wall ofouter passageway 219 and are open ended which means that the portscommunicate with chamber 216. The ports 224 do not extend entirely alongthe wall of passageway 219. Rather, the ports terminate partway alongthe wall such that a smooth wall portion 225 extends between the end ofports 224 and inlet 210. The reason for this will be described ingreater detail below.

Part 218 contains a standard luer lock fitting 226 which extends aboutpassageway 222 and which functions to allow a needle etc to be attachedto this part of the assembly. Of course, other types of attachments canalso be used.

Inner passageway 221 has a diameter that is smaller than innerpassageway 220. Thus, the wall 227 of inner passageway 221 passes intoinner passageway 220 this being best illustrated in FIG. 23. Moreover,wall 227 has a length that results in the wall 227 being spaced somewhatfrom wall 228 of top part 217 (see FIG. 23). This spacing facilitatesthe attachment of the elastic web that will be described in greaterdetail below.

Plunger 212 is formed of plastic material and comprises a unitary body.The plunger has a particular configuration that provides a nose portion213, and a rear body portion 229. Nose portion 213 is slightly taperedand has a through passageway 230 which passes through an open outer end231 and functions to allow fluid to flow through the valve assembly.Body portion 229 is provided with a transverse through bore 232 throughwhich fluid can pass. Body portion 229 has a substantially cylindricalouter wall provided with an entry seal 235. This is why the fluid ports224 in end wall 225 terminate short of inlet 210 to also provide asmooth area which functions as a sealing zone 236. Thus, when theplunger is in the closed position illustrated in FIG. 23, the sealingcollar 235 seals against the sealing zone 236 to provide seal againstfluid flow.

When plunger 212 is pushed forwardly from the position illustrated inFIG. 23 to the position illustrated in FIG. 22, the plunger only movesby a few mm, but this movement is sufficient to move seal 235 away fromsealing zone 236 and into the area of the flow ports 224 and to allowfluid to pass along the outside wall of body portion 229, through thefluid ports 224, through bore 232 through passageway 230 and throughoutlet 211. Conversely, when the plunger is retracted from the positionillustrated in FIG. 22 to the position illustrated in FIG. 23 theplunger again seals against passage of fluid from inlet 210 throughoutlet 211.

Fluid only flows when the flow ports 224 are opened by seal 235 movingpast the outer most edge of the flow ports. At all other times a seal ismaintained between the internal wall 225 and collar 235.

The plunger is biased back to its retracted position by the elastic web214 which also provide additional functions. Elastic web 214 is made ofa rubbery elastic material having an excellent memory. The elastic webis substantially circular and has a base portion 239 with a peripheraledge 241 that is thickened with respect to the thickness of the baseportion immediately next to the peripheral edge. The thickenedperipheral edge 241 is trapped between wall 227 of part 218 and theinner wall of part 217. Peripheral edge 241 also functions to seal thefluid pathway in the apparatus.

The plunger 212 has an annular seal 215 on body portion 229. The annularseal 215 is positioned on body portion 229 such that when the plunger isin the retracted or closed position illustrated in FIG. 23, the annularseal sits between body portion 229 and an internal wall of the valve.The annular seal provides two functions. The first function is to stopdirect contact between the plunger and the internal wall of the valveand thereby to reduce wear and tear. The second function is to close offthe variable volume chamber 216 when the variable volume chamber is inthe smaller position. Thus, when the plunger is in the closed position,the variable volume chamber is isolated from the remainder of the fluidpathway in the valve and there is no possibility of any fluid passinginto the variable volume chamber or flowing from the variable volumechamber when the plunger is in the retracted closed position.

The nose portion of the plunger is provided with an outlet seal 242.

As the plunger 212 is pushed to the forward open position, it willstretch the biasing web 214 which forms part of the variable volumechamber 16 and the movement will increase the volume of chamber 216.When the plunger is retracted to the closed position (and web 214 formspart of a biasing means to bias the plunger back to the closedposition), the variable volume chamber will reduce in volume and willprovide a positive pressure in the valve to prevent backflow of anyfluid into outlet 211. This arrangement is similar to that described inour earlier international patent application.

The web is designed such that when the plunger 212 is in the retractedclosed position, there is still some tension in the web to keep theplunger in the retracted position.

A small air passageway 256 is provided to allow air to pass into chamber223 upon shrinking of the web and to allow air to pass out of chamber223 upon stretching of the web.

The valve assembly prevents back flow of fluids by maintaining apositive pressure in chamber 216.

Another advantage with the arrangement is that possibly contaminated airis kept separate from the fluid flow pathway of the valve assembly byvirtue of the web 214 and the various seals.

It should be appreciated that various other changes and modificationscan be made to the invention without departing from the spirit and scopeof the invention.

1. A one way valve assembly that comprises: an inlet and an outlet, aflow pathway that extends through the valve assembly from the inlet tothe outlet, a plunger that is positioned in the flow pathway and whichcan move between a forward open position where fluid can flow from theinlet to the outlet, and a retracted closed position where fluid flow isreduced or prevented from flowing from the inlet to the outlet, an atleast partially elastic diaphragm that has an outer end fixed to thevalve assembly, and an inner portion which engages with the plunger suchthat reciprocation of the plunger from the retracted position to theforward position causes at least part of the diaphragm to stretch, avariable volume chamber having walls at least partially defined by theplunger and the diaphragm, the chamber forming part of the flow pathway,the chamber having smaller or nil volume when the plunger is in theretracted position, and a larger volume when the plunger is in theextended position, whereby upon retraction of the plunger, the variablevolume chamber reduces in volume which results in a pumping action topump fluid through the fluid pathway towards the outlet, therebyreducing or preventing backflow, and a resilient end valve positionedwithin the flow pathway adjacent the inlet and supported by a spacingmember, the spacing member being co-axially aligned with the flowpathway and attached to the plunger, the resilient end valve beingmovable between an open flexed position enabling fluid to flow towardsthe outlet of the valve, and a closed rest position preventing backflowof fluid through the inlet, wherein the resilient end valve is moved tothe open flexed position by the flow of fluid, and the resilient endvalve is moved to the closed rest position by the absence of flow offluid.
 2. The assembly as claimed in claim 1, wherein the resilient endvalve is naturally biased to the closed rest position and is moved tothe open flexed position by the flow of fluid through the inlet and willmove to the naturally closed rest position when the flow of fluid stops.3. The assembly as claimed in claim 2 wherein the plunger is a slidingplunger that is moved from the retracted position to the forwardposition upon insertion of a tip into the inlet of the valve assembly,and moves from the forward position to the retracted position uponremoval of the tip from the inlet.
 4. The assembly as claimed in claim3, wherein the resilient end valve moves with the plunger such that whenthe plunger moves between the forward position and the retractedposition.
 5. The assembly as claimed in claim 4, wherein the plunger hasa base part that is adjacent the inlet of the valve assembly, thespacing member towards the inlet from the base part, and has a smallercross-section size than resilient end valve to support a central portionof the resilient end valve, the resilient end valve comprises adisk-like member having a peripheral edge that can flex relative to thecentral portion, the peripheral edge able to flex between a closed restposition where the peripheral edge prevents fluid from backflowingthrough the valve assembly, and a flexed open position where fluid canflow through the valve assembly, the resilient end valve flexing to theopen position by the pressure of fluid flowing through the inlet, andreturning to the closed rest position upon reduction of the fluidpressure through the inlet.
 6. A one-way valve assembly that comprisesan inlet and an outlet, a variable volume chamber which increases involume as fluid flows through the assembly from the inlet to the outlet,and which decreases in volume upon removal of a tip from the inlet, orupon slowing or stopping of fluid flow from the inlet to the outlet, thedecrease in volume providing a positive pressure to reduce or to preventbackflow, and a resilient end valve positioned within the flow pathwayadjacent the inlet and at least partially supported by a spacing memberthat is co-axially aligned with the flow pathway and attached to aplunger, the resilient end valve being movable between an open flexedposition where fluid can flow from the inlet to the outlet, and a closedrest position where backflow is reduced or prevented, the resilient endvalve being movable from the closed rest position to the open flexedposition by fluid pressure, and being movable from the open flexedposition to the closed rest position upon a reduction or stopping of thefluid pressure.
 7. A medical fluid dispensing device having: a bodyadapted to contain fluid, a tip defined by the body with a forwardopening through which fluid is dispensed, and a mechanism for dispensingfluid via the tip; and a one-way valve assembly that comprises: an inletand an outlet, wherein the tip of the medical fluid dispensing device isinserted into the inlet of the valve assembly, a flow pathway thatextends through the valve assembly from the inlet to the outlet, aplunger that is positioned in the flow pathway and which can movebetween a forward open position where fluid can flow from the inlet tothe outlet, and a retracted closed position where fluid flow is reducedor prevented from flowing from the inlet to the outlet, an at leastpartially elastic diaphragm that has an outer end fixed to the valveassembly, and an inner portion which engages with the plunger such thatreciprocation of the plunger from the retracted position to the forwardposition causes at least part of the diaphragm to stretch, a variablevolume chamber having walls at least partially defined by the plungerand the diaphragm, the chamber forming part of the flow pathway, thechamber having smaller or nil volume when the plunger is in theretracted position, and a larger volume when the plunger is in theextended position, whereby upon retraction of the plunger, the variablevolume chamber reduces in volume which results in a pumping action topump fluid through the fluid pathway towards the outlet, therebyreducing or preventing backflow, and a resilient end valve positionedwithin the flow pathway adjacent the tip and a supporting spacing membersuch that the resilient end valve is positioned between the tip and thespacing member, the spacing member being co-axially aligned with theflow pathway and attached to the plunger, the resilient end valve beingmovable between an open flexed position enabling fluid to flow towardsthe outlet of the valve, and a closed rest position preventing backflowof fluid through the inlet, wherein the resilient end valve is moved tothe open flexed position by the flow of fluid, and the resilient endvalve is moved to the closed rest position by the absence of flow offluid.